3,3&#39;disubstituted benzidine derivatives

ABSTRACT

Disclosed are disubstituted benzidine derivatives having on both the 3- and 3&#39;&#39;-position a substituent W-X-A-On-, subscript n is zero or one, A is a divalent lower alkylene chain with from about 2 to about 7 carbons, X is the divalent carbonyloxy or sulfonyloxy group, W is hydrogen or other chromogen-reactiveindicator compatible cation; and the chromogen-reactive-indicator compatible acid addition salts of those benzidine derivatives. Also disclosed is the improvement in an analytical test, wherein is used a color change reagent preparation comprising peroxidase, an oxygen-oxidoreductase specific to a particular substance to be tested and for which there exists a specific oxygenoxidoreductase, and a chromogen-reactive-indicator which is one of the foregoing disubstituted benzidine derivatives or a chromogen-reactive-indicator compatible acid addition salt of it.

United States Patent 11 Jonsson et al.

Jan. 7, 1975 i 1 3,3DISUBSTITUTED BENZIDINE DERIVATIVES [75] Inventors: Nils Ake Jtinsson, Sodertalje;

Merenyi: Ferenc; Lars-Erik Westlund, both of Taby, all of Sweden [73] Assignee: A B Kabi, Stockholm, Sweden [22]' Filed: Feb. 24, 1971 [21] Appl. No.: 118,531

[30] Foreign Application Priority Data Mar. 6, 1970 Sweden 2976/70 [52} US. Cl. 260/518 R, 195/1035 C, 260/401, 260/404.5, 260/501.12, 260/509, 260/519 [51]' Int. Cl. C07c 101/44 [58] Field of Search 260/518 R, 519, 4045, 260/501.l2

[56] References Cited UNITED STATES PATENTS 2,724,722 11/1955 Bossard et al. 260/519 Primary Examiner-Lorraine A. Weinberger Assistant ExaminerL. A. Thaxton Attorney, Agent, or FirmA. A. Orlinger [57] ABSTRACT Disclosed are disubstituted benzidine derivatives having on both the 3- and 3-position a substituent W-X AO,,, subscript n is zero or one, A is a divalent lower alkylene chain with from about 2 to about 7 carbons, X is the divalent carbonyloxy or sulfonyloxy group, W is hydrogen or other chromogen-re'active indicator compatible cation; and the chromogenreactive-indicator compatible acid addition salts of those benzidine derivatives.

Also disclosed is the improvement in an analytical test, wherein is used a color change reagent preparation comprising peroxidase, an oxygen-oxidoreductase specific to a particular substance to be tested and for which there exists a specific oxygen-oxidoreductase, and a chromogen-reactive-indicator which is one of the foregoing disubstituted benzidine derivatives or a chromogen-reactive-indicator compatible acid addition salt of it.

10 Claims, No Drawings ,3,3 -DISUBSTIT.UTED BENZIDINE DEBAYITIYES or the sulfonyloxy group and W is hydrogen or other chromogen-reactiveindicator compatible cation (as hereinafter defined) such as an alkali metal as sodium or potassium.

These new 3,3'-disubstituted benzidine derivatives are primarily stable chromogens. They include also their chromogen-reactive-indicator compatible acid addition salts (as herein below defined), for example, their hydrogen halogenic acid addition salts such as their di-hydrohalides with any of the hydrogen halides as hydrobromic, hydrofluoric, or hydriodic acid, and particularly hydrochloric acid as in the dihydrochloride salt of the 3,3'-disubstituted benzidine derivative, their hydrogen sulfates (from the use of sulfuric acid), or the sulfonates such as provided by use of aryl sulfonic acids as the mononuclear such acidsas phenylsulfonic acid and toluenesulfonic acid, and binuclear such acids as napththalene sulfonic acid.

These 3,3-disubstituted benzidine derivatives (including their acid addition salts) of the invention are useful as the oxidizable chromogen constituent of a chromogen-reactive-indicator composition which in addition to the chromogen comprises peroxidase and an oxygen-oxidoreductase, for example, specific to a particular sugar to be tested for, such as glucose oxidase or galactose oxidase; and which reactive-indicator composition is used in the well known analytical method wherein hydrogen peroxide forms during the analytical reaction and serves to act on the oxidizable chromogen (that is to say, in its reduced state) to con vert it to the oxidized state wherein it provides a visible color change in the presence of the particular substance such as a sugar being tested for.

Another part of the invention is the resulting chromogen-reactive-indicator compositions containing as their chromogen constituent a 3,3'-disubstituted benzidine derivative (or acid addition salt thereof) of the invention, along with the use of these compositions in an analytical procedure applied, for example, to sugars by use of such chromogen-reactive-indicator composition as in the qualitative or quantitative detection of such a sugar as glucose or galactose.

In a number of such analytical methods wherein hydrogen peroxide is formed during the analytical reaction it acts on a suitable chromogen compound which in its reduced state does not absorb light in the visible range of the spectrum, to convert the chromogen to its oxidized state which does absorb visible light.

Such analytical methods are used, for example, in the assay of individual sugars such as glucose, galactose, wherein an oxidase specific for the sugar involved, that is to say, an oxygen-oxidoreductase such as glucose oxidase or galactose oxidase, acts solely on the type of sugar to be determined, with formation of hydrogen peroxide. The latter under the influence of peroxidase enzyme, that is hydrogen-peroxide-oxidoreductase, oxidizes the chromogen compound with change of color proportionate to the concentration of the sugar.

The briefly earlier used nomenclature including the term oxidoreductase is in accordance with the Enzyme Commission Classification System. Accordingly, Thomas, E. Burmans Enzyme Handbook, Springer- Verlag, Berlin, Heidelberg, N.Y., 1969, shows that all enzymes taking part in any redox-process are called oxidoreductases. Those which catalyze the reaction wherein oxygen is an electron acceptor are called oxygen-oxidoreductases. Those which catalyze reactions wherein hydrogen peroxide is an electron acceptor are called hydrogen-peroxide-oxidoreductases.

Other similarly behaving analyses are, for example, the determination of (i) uric acid with the use of uricase, or (ii) an amino acid with the aid'of the corresponding amino acid oxidase, or (iii) pyridoxaminephosphate by pyridoxaminephosphate oxidase.

Chromogen-reactive-indicators are well known in the art by their inclusion as the color change indicating constituent or chromogen in chromogen-reactiveindicator compositions widely used, for example, to impregnate test strips such as those reactive-indicator compositions comprising peroxidase, an oxidizable chromogen forming a differently colored oxidation product in the presence of the peroxidase, and an oxidase specific, for example, to a particular sugar such as glucose or galactose being tested for, as illustrated in the copending allowed application of Arne Lennart Dahlqvist, Ser. No. 606,498 filed Dec. 16, 1966 now US. Pat. No. 3,598,704; and page 16 below.

Thus, the earlier above-mentioned chromogenreactive-indicator compatible cation is one other than hydrogen which, when present as the carboxylate or sulfonate-forming cation in a 3,3'-disubstituted benzidine derivative of the invention, is compatible with, by being inert to, the hydrogen peroxide, the peroxidase, and the further enzyme as the oxygen-oxidoreductase, such as glucose oxidase or galactose oxidase, included in the chromogen-reactive-indicator composition, and to any buffer included in the composition.

Similarly, the chromogen-reactive-indicator compatible acid addition salt of the 3,3'-disubstituted benzidine derivative of the invention is an addition salt of the specific derivative and prepared by the use of an inorganic or organic acid which when combined with the derivative to form an acid addition salt of it leaves the resulting acid addition salt compatible, in that it is inert to, the just foregoing referred to constituents of a chromogen-reactive-indicator composition.

In these analytical tests, certain simple benzidine derivatives, such as o-dianisidine and o-tolidine, have attained wide practical use as the chromogens. In their oxidized state light absorption occurs within the wave length range of about 450 nanometers (nm), and there is found a direct relationship between the color extinction and the amount of the sugar or other component to be determined.

The chromogens used heretofore, however. manifest certain disadvantages. For example, the low solubility of the earlier used benzidine derivatives, being about 100 mg./liter in the reduced state and about mg./liter in the oxidized state, is a drawback. Therefore, the color that they provide must be observed and recorded within a short time span. Furthermore, the color of oxidized o-dianisidine is sensitive to light. When exposed to light, its extinction can decline quickly to the extent of up. to 25 percent, resulting in incorrect and widely varying results. The time required for the development of color at about 450 nm is disturbingly long in determinations where o-dianisidine and o-tolidine are used. 4

With them, at room temperature a color development time of between 50 to '60 minutes often is required. Then too, the tubing material used in the analytical instruments absorbs oxidized o-dianisidine and vention to attain chromogens with properties suitablefor the higher demands of modern analytical activity, resulted in the herein described new class of chromogen compounds meeting these demands andhaving the following general formula: I

, war-A4), on-'A-x w I as well as their earlier herein mentioned chromogenreactive-indicator compatible acid addition salts, and in which formula the subscript n is zero or one, A is a divalent lower alkylene chain with from 2 and beneficially at least 3 to about 7 carbons, and X and W separately are defined as recited respectively earlier above (in the first paragraph of this specification). The group XW is either the carboxyl or sulfonic acid group,

or the carboxylate or sulfonate group whenW is a chromogen-reactive-indicator compatible cation other than hydrogen.

The 3,3'-disubstituted benzidine derivatives, the new class of chromogens of the invention, can be obtained by various methods including different combinations of steps. Initially in each individual procedure the availability of.a suitable starting material is important. In preparing the compounds of the general formula for the 3,3-disubstitutedbenzidine derivatives of the invention, wherein n is 1, it is beneficial, for example, to start with the commercially readily available 0- dianisidine. Reference to its formula,

shows that by demethylation of the methoxy groups and acylation of the amino groups to block them, 0- dianisidine can be converted to the corresponding diphenol. Suitable groups for blocking the amino groups are the amino-groupblocking acyl groups, for example, the acetyl, benzoyl, of phthalyl group. Before seeking to introduce the desired side chain or substituent at the 3- and 3'-positions, the diphenol suitably should be' converted into phenolate form, i.e. the diphenolate salt, perferably its sodium or potassium di-phenolate, by reaction with an alkalizing agent, for example, an alkali metal hydride suchas sodium hydride, or an alkali metal alcoholate as sodium alcoholate or potassium alcoholate. Then the coupling of the desired side chain with the thus formed phenolate groups can be carried out in a suitable inert solvent such as dimethylformamide, or an alcohol, or possibly in aqueous solution. In the latter case the conversion of the hydroxyl groups to phenolate salt easily can be done with an alkali metal hydroxide.

Compounds suitable for use in introducing the desired substituent chain O,,-A-'*XW have the general formula ZAJ, whereinA has its earlier above recited scope, Z is a halogen atom (e.g. chlorine, bromine, or iodine) or an arylsulfonyloxy group such as phenylsulfonyloxy, toluylsulfonyloxy, or naphthylsulfonyloxy; and when X in the general formula of the desired end product is to be carbonyloxy, then .l is the carboxyl group or a group convertible to it such as the cyano group or an alkoxycarbonyl group.

In the specific case where A is dimethylene (CH- the coupling can be carried out by addition of acrylonitrile. When X in the formula for the end products is to be the sulfonyloxy group, I can be, for example,

a halogen atom (as earlier above exemplified) or hydroxyl. Either of them thereafter can be converted in known manner into a sulfonic acid group. Also J and Z can jointly form the sulfonyloxy group of a sultone ring such as propanesultone or butanesultone,'as shown by Examples 3 part (a) and 4. Any of these cyclic esters may be alkylated on its lower alkyl portion.

Further effective compounds having the formula Z AJ are, for example, beta-chloropropionitrile, gamma-chlorobutyronitrile,

. gammachlorobutyroamide, as well as the corresponding bromo-compounds, and gamma-p-toluene sulfonyloxy butyronitrile.

After the introduction of the side chain on the phenyl rings, the blocking groups are removed from the amino groups in known manner, e.g. by hydrolysis.

By another procedure, o-dianisidine can be used as the starting material in such a way that it first is converted into 3,3' -dihydroxy-4,4'-dinitrodiphenyl. That, in the same manner as described above about the use of the compounds having the formula Z-'AJ, is coupled with a such compound to provide the desired 3,3

. side chain. Thereafter the nitro groups are converted into amino groups by reduction in known manner.

In cases where the subscript min the general formula for the end products is zero and X is the carbonyloxy group, the preparation of these products preferably starts with a lactam having the formula nation into the corresponding benzo-ring-substituted halogen, beneficially iodo, derivatives having the following general formula:

Hal

After blocking the imino group in this halogen derivative by addition of a blocking residue such as an acylic or sulfonyloxy residue, and reacting the thus blocked halogen derivative with copper (as by the Ullmann reaction), the halogen is removed from the benzene ring with resulting linking together of two of them whereby the imino-group block derivative is converted into the corresponding (similarly-blocked) biphenyl derivative with the following general formula:

wherein A is the same as in the just preceding formula. These biphenyl derivatives (with a fused heterocyclic ring on each benzene ring) upon either alkaline or acid hydrolysis, forexample, as seen in part (d) of each of Examples 5 and 6, yield the desired 3,3'-disubstituted benzidine derivative.

Illustrative products of the invention obtained by various of the disclosed methods for their preparation are shown by, but not to be restricted to, the following examples: 1

EXAMPLE 1 Gamma,gamma'-(4,4 '-diamino-'3 ,3 '-biphenyldioxy dibutyric acid dihydrochloride a. Toa suspension of 16 grams of sodium hydride in 800 milliliters of anhydrous dimethylformamide, a total of 90 gm. of 4,4'-diacetamino-3,3'-dihydroxybiphenyl is added-in small portions under agitation in a nitrogen atmosphere, following which the temperature is kept at about -5C. by cooling in a cooling bath. The mixture is agitated for about 1 hour until the liberation of hydrogen ceases. Under continued cooling 90 gm. of methyl gamma-chlorobutyrate is added dropwise. The cooling bath then is removed and the temperature is allowed to increase to about 20C. The introduction of nitrogen is stopped and the temperature is increased successively to 80C. and maintained overnight. The

major part of the solvent is distilled off under vacuum on a water-bath, and the residue-in the flask is poured into 2 liters of ice water under agitation. After about a couple of hours, the product is decanted and thoroughly washed with water. The crude product is allowed to dry, and then is dissolved in 2 liters of boiling 2-propanol and filtered. After cooling, 110 gm. (73%) of methyl gamma,gamma'-(4,4'-diacetamino-3,3'- biphenyldioxy)dibutyrate are obtained. A sample recrystallized from 2-propanol melts at 152 to 160C.

b. 74 gm. of this methyl ester end product of part (a) are added in portionsunder agitation in a nitrogen atmosphere to a solution of 27 gm. of sodium hydroxide in 450 ml. of water and 450 ml. of methanol, during which procedure the temperature is kept at 20C. for about 20 hours and thereafter at 50C. for 6 hours. The major part of the methanol then is distilled off under vacuum. The remaining solution is diluted with 1.5 liters of water and'filtered. After further dilution with 3 liters of water, the free gamma,gamma-(4,4' diacetamino-3,3'-bipheny1dioxy)dibutyric acid is precipitated by cautiously adding 2 N hydrochloric acid c. The precipitated compound is separated and washed with water. Yield 90%. The crude product is dissolved in about 750 ml. of boiling acetic acid and hot water (about 400 ml.) is added until a slight haze appears. 30 gms. of decolorizing carbon are added and the mixture agitated and filtered while hot. On cooling,

the purified product crystallizes out and is filtered off and on drying yields 49.7 gm. (71%) melting at 214-217C.

d. 40 gm. of this purified end product of part (c) are boiled under reflux for 6 hours with 500 ml. of concen trated hydrochloric acid' The resultingcrystalline paste isdecanted and washed with concentrated hydrochloric acid. For purification this paste is dissolved in the necessary quantity of boiling water, and thereafter concentrated hydrochloric acid is added until crystallization begins. After cooling, the produce is decanted, washed with concentrated hydrochloric acid and dried under vacuum over solid potassium hydroxide. Yield dihydrochloride of diamino-3,3'-biphenyldioxy)dibutyric acid. The product decomposes when heated without any defined melting point.

EXAMPLE 2 Gamma,gamma'-( 4,4'-diamino-3 ,3 '-biphenyldioxy)- dibutyric acid EXAMPLE 3 Gamma,Gamma-( 4,4'-Diamino-3 ,3 '-Biphenyldioxy)- Dipropane Sulfonic Acid a. To a solution of 26.7 gm. of sodium hydroxide in 300 ml. of methanol is added gm. of 4,4- diacetamino-3,3'-dihydroxybiphenyl. After this diphenol has dissolved, there is added a suspension of 73.3

gms. of gamma-propanesultone in 200 ml. of methanol. The mixture is heated at 85C. for 1 hour resulting in a crystallineslurry. After cooling it, the mother liquor is decanted from the product which then is washed with cold methanol. For purifying the crude disodium salt of gamma,gamrna'-(4,4'-diacetamino-3,3'biphenyldioxy)dipropane sulfonic acid, it is suspended and stirred in 500 ml. of methanol, and the latter-is decanted. After drying, 108 gm. of a light brown compound are ob.- tained, with decomposes without a defined melting point.

b. A solution of 40 gm. of the disodium salt product of part (a) of this example in 250 ml. of water is filtered through a column charged with a strong hydrogen ionsaturated ion exchanger. The filtrate free from sodium ions is boiled with 500 ml. of concentrated hydrochloric acid'for 2 hours under reflux and then is evaporated until crystallization begins. After cooling, the mother liquor is decanted and the crystalline product is washed with methanol. For purification, the crude product is dissolved in 1.2 liters of boiling water, treated with decolorizing charcoal and filtered. After cooling, there crystallized out 11.7 gm. of gamma,gamma-(4,4'- diamino-3,3'-biphenyldioxy)dipropane sulfonic acid which decomposes without a defined melting point about 300C. Upon concentration of the filtrate, additional 8.7 grns. of product are obtained.

EXAMPLE 4 Delta,Delta '-(4,4 -Diamino-3 ,3 '-Biphenyldioxy)Dibutane Sulfonic Acid sultone reacted with 4,4-

Delta-butane is diacetamino-3,3-dihydroxybiphenyl in thesame man- EXAMPLE 5 Y Gamma,Gamma-(4,4'-Diamino-3,3'-

Biphenyl)Dibutyric Acid a. 32.2 gm. of 2-oxo-2,3,4,5tetrahydro-1-H-1- benzazepine are dissolved in 300 ml. of'glacial acetic acid. A solution of 32.5 gm. of iodine monochloride in 200 ml. of acetic acid is added under agitation. The mixture is kept for 48 hours at room temperature and is diluted with a large volume of water to precipitate the desired intermediate. The mother liquor is decanted and the precipitated intermediate product is washed with water and recrystallized from a mixture of methanol and water (in manner much like the recrystallization described on page lines 3 to 7 hereof. The purified 7-iodo-2-oxo-2,3 ,4,5 -tetrahydrol -H- l benzazepine melts at 187 to 188C.

dimethyl formamide and 20 gm. of copper powder are agitated under reflux for 3 hours. Then 20 more gm. of copper powder are added and the mixture is heated and agitated for another 12 hours. The resulting solid substance is filtered off and washed with dimethyl formamide. The combined filtrate and washings are evapo-. rated under vacuum to a small volume. After addition of water, 4.6 gm. of a solid compound are obtained, which is dissolved in a 50% mixture of methanol and water. The solution is filtered, some sodium hydroxide solution is added, following which contaminations are precipitated, and filtered off. Addition of 2 N hydrochloric acid to the filtrate precipitates out of it 7,7- bis(2-0xo-2,3,4,5-tetrahydro-l-H-l-benzazepine) as colorless crystals which after transformation decompose at about 178C. without any defined melting point above 300C.

d. 1 gm. of this 7,7-bis-benzazepine derivative from part (c) of this example is heated with 140 gm. saturated barium hydroxide solution for 7 hours at 150C.

' in an autoclave. After cooling, an aqueous solution of sodium carbonate is added in a slight excess over that needed to precipitate all of the barium. The precipitated barium carbonate is filtered off and the gamma,gamma'-(4,4'-diamino-3,3'-biphenyl)dibutyric acid is precipitated from the filtrate by addition of acetic acid j to about pH 5. The product decomposes without a deb. 10 gms.'of the 7-iodo-2-oxo-2,3,4,5-tetrahydro-l- H-l-benzazepine from part (a) of this example are refluxed for 6 hours with 160 ml. of acetic anhydride. The solution is evaporated under vacuum following which a thick oil is obtained, which when admixed with fined melting point at about C.

EXAMPLE 6 Example 5, by its same procedure thereis obtained N- acetyl-8-iodo-2-oxo-1,2,3,4,5,6-hexahydro-lbenzazocine.

c. By using an equivalent amount of this N-acetyl-8- iodo-2-'oxo-1,2,3 ,4,5,6-hexahydro-1-benzazocine of part (b) of this example in place of thecorresponding N-acetyl-8-iodo-2-oxo-benzazepine product of part (c) of Example 5 and following its procedure, there is obtained instead 8,8-bis(2-oxo-1,2,3,4,5,6-hexahydro-1- benzazocine).

d. 10 gm. hexahydro-l-benzazocine) arev refluxed for 12 hours with'200 ml. of concentrated hydrochloric acid. The

solution is evaporated to a small volume, diluted with water, following which the pH is adjusted to 5 to 6 by adding concentrated sodium acetate solution. The precipitated delta,delta-(4,4'diamino-3,3 '.'-biphenyl)divaleric acid is filtered off and washed with water yielding a greyish crystal powder which readily discolors in the air and decomposes without any defined melting point.

The end products of each of Examples 2, 3(b), 4, 5(d) and 6(b), and any other such 3,3'-(di-lower alkanoic acidor disulfonic acid)-substituted benzidine derivative can be converted to the respective dicarboxylates or disulfonates, i.e. where W is a cation other than of this 8,8'-bis(2-oxo-l,2,3,4,5,6--

hydrogen, by stirring'the carboxylic or sulfonic acid product in an amount of an aqueous solution (sufficient to allow suitable agitation) of, for example, an alkali metal,'such as sodium or potassium, hydroxide suffrcient to neutralize the quantity of the carboxylic or sulfonic acid product. The resulting respective dicarboxylate or disulfonate then is separated, for example, by carefully evaporating the aqueous solution to allow the product to crystallize-out or to dryness if necessary.

The concentrated hydrochloric acid used to prepare the dihydrochloride acid addition salt as of Example l(d) can be replaced by some other acid used with any modification in reaction conditions as may be needed to be made for its use to produce some other desired acid addition salt of that 3,3'-disubstituted benzidine derivative or any of the others produced by variations in the reactants. For example, other acid addition salts may be prepared by using sulfuric acid or an organic sulfonic acid whether aliphatic such as methylene sulfonic acid or mononuclear aromatic as benzene sulfonic acid or alkyl-substituted mononuclear-as toluene sulfonic acid, or binuclear as napthalene sulfonic acid. It is understood that the specific starting material or reactants used in any of the foregoing examples can be replaced by others effective to provide in the end product any desired variations within the nature of the sub- .dibutyrate. So also, gamma-bromobutyronitrile can be used and provides instead gamma,gamma-(4,4'- diacetoamino-3,3 '-biphenyldioxy)dibutyronitrile melting at 246C., but this intermediate subsequently would need to be hydrolyzed to convert the nitrile groups to carboxyl.

In addition, any of the reagents used in carrying out certain of the reactions such as (i) the blocking of the 4,4-diamino groups or theimino group as in the benzazepine or benzazocine starting material can be replaced by some other compatible blocking or acylating agent for blocking the activity of a reactive hydrogen of an amino or imino group, or (ii) the hydrolysis steps used in some of the examples.

The utility of the 3,3'-disubstituted products of this invention as chromogen compounds is the basis of a further part of this invention, namely, chromogenreactive-indicator compositions useful in analytical procedures such as those described earlier above. These compositions comprise as their chromogen constituent a 3,3'-disubstituted benzidine derivative of this invention, a hydrogen-peroxide-oxidoreductase as which peroxidase is used, a specific oxygenoxidoreductase for the specific material in the testing for which such composition of this invention will be used, such as glucose oxidase when testing for glucose,

' galactose oxidase in testing for galactose, uricase in making determinations of uric acid, pyridoxaminophosphate oxidase in determining pyridoxaminophosphate, and the specific amino acid oxidase in making determinations of a specific amino acid. These three essential constituents generally are dissolved in distilled Chromogen used 0.2 mM (i.e. millimolar),

peroxidase 300 units,

glucose oxidase 3000 units,

phosphate buffer to pH 7 0.1 M, and distilled water to make 1000 ml.

Stock or test solutions were prepared containing glucose in concentrations of 25, 50, 100, 200, 300, and 400 mg. per ml.

When routinely using reagents or testing compositions according to the just above described plan, determinations of biological, protein-containing materials, for example, blood, also are made. In such cases, initially a precipitation of proteins is made, for example, with 0.33 M glycine-buffered perchloric acid to pH 2.7, after which the sample is diluted 1 part to 21. Before the final determination, this thus diluted solution is diluted further 1 part to 11 with just the above described chromogen reagent solution. Thereafter the development of color is measured at 450 nm.

When this particular dilution patternis applied to the foregoing stock or test stern solutions, finally diluted solutions with the following respective glucose contents are obtained:

2.2, 4.3, 8.6, 13.0, and 17.3mg. per liter.

The chromogen-reactive-indicator compositions of the invention, and the improved testing method involving their use are illustrated by, but not restricted to, the following examples:

Example A Chromogen of Example l(d): A chromogen-reactive-indicator preparation of the foregoing standard constitution with 0.2 mM gamma,gam-,

ma'-(4,4'-diamino-3,3-biphenyldioxy)dibutyric acid di HCl of Example l(d) as a chromogen was evaluated bythe foregoing standard protocol against the various glucose stock solutions. Maximum color development at 450 nm occurred within 25 minutes at 25C. and within 15 minutes at 37C. respectively. The solubility in water of this acid addition salt used as the new chromogen was very good, and no precipitation of chromogen occurred. its color stability at its extinction maximum enabled reading at an optional time up to 4 hours.

For use in automatic analyzers, it is desirable that the rubber or various plastic materials forming part of the tubing should not be discolored by the chromogencontaining reagent solution. Samples of various kinds of tubings were immersed for 25 hours separately respectively in chromogen-reactive-indicator reagent i compositions of the foregoing constitution, one of them having as its chromogen the product of Example l(d) orlcss whereas those tube samples immersed in the reagent composition containing the o-dianisidine turned brown. As to these latter, to the extent that reactions occurred between the o-dianisidine and the tube material, analyses using it yield incorrect results.

Example B Chromogen of Example 3(b): A chromogen-reactive-indicator reagent .preparation of the foregoing standard constitution with 0.2 mM. gamma,gamma-(4,4' -diamino-3,3-biphenyldioxy)diprov pane sulphonic acid of Example 3(b) as-its chromogen was evaluated by the foregoing standard procedure against the various glucose stock solutions. Maximum color development at 430 to 450 nm occurred within 25 minutes at 25C. The solubility in water of the new chromogen is quite good, and thus no precipitation of it occurs. The color stability of this chromogen of Example 3(b) at extinction maximum enables reading at an optional time up to 4 hours, which was the longest period over which the test material was observed.

Like analytical tests of the compounds of the other examples show that these properties exhibited by the two chromogens of Examples 1(d) and 3(b) are manifested also by the other chromogens embraced by the general formula covering the compounds of this invention. Comparisons of the behavior of the commonly used benzidine derivatives o-dianisidine and o-tolidine with the chromogens of these examples of this invention show results given in the'following table:

e tllieihaym lhsssasra @929 metal cation.

3. The 3,3'-disubstituted benzidine derivative as claimed in claim 1, wherein n is one.

4. The 3,3-disubstituted benzidine derivative as claimed in claim 3, wherein W is hydrogen.

5. Gamma,gamma'-(4,4'-diamino-3,3'-biphenyldioxy)dibutyric.acid.

Solubility at pH 7 Extinction Time for color development mg/liter decrease (in minutes) Wave after irradia- Absorption length tion 5 min' by 1 7 range reduced oxidized under 40 Watt tubing Chromogen used. in nm pH-value (uncolored) (colored) tungsten lamp C 37C material o-dianisidine 450 6.5 H0 10 26 5O o-tolidine 430 6.5 130 7 l 60 o-tolidine 630 4.5 130 7 unstable l0 6 Product of Example 1(d) 450 6.5 70000 700 2 25. I5 Product of Example 3 (b) 6.5 12000 understood that various modifications and substitutions may be made in any of them within the scope of the appended claims which are intended also to include equivalents of the disclosed specific embodiments.

What is claimed is:

l. 3,31-disubstitutedbenzidine derivative selected 6. A hydrogen halogenic acid, sulfuric acid, phenylsulfonic acid, toluene sulfonic acid or naphthalene sulfonic acid addition salt as claimed in claim 1, wherein n is l, A is a divalent trimethylene group, and W is hydrogen.

7. The dihydrochloride of the 3,3'-disubstituted benzidine derivative as claimed in claim 6.

8. The 3,3'-disubstituted derivative as claimed in claim 1, wherein n is zero.

9. The 3,3'-disubstituted derivative as claimed in claim 8, wherein W is hydrogen. v

10. Delta,delta-(4,4'-diami no-3 ,3 '-biphenyl)divaleric acid. 1

UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3 859 ,341 7 Dated l'y 7 1975 Nils Ake Jonsson et a1 Page 1 of- 2 Inventor(s) It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In item I54], after "3, 3" insert a hyphen. Column 2, line 15, "N.Y." should read NewTork line 43, after "carboxylate" add a hyphen. Column 4, line 6, "of" should read or line 22, "0 A-X-W" should read -0 -A-XW Column 7,

line 10, "with" should read which line 55, "page 10 lines 3 to 7" should read column 6 lines 23-29 Column 11,

lines 48-49, "shown above where glucose oicidase was tested" should read given at column 10 lines 10 to 19 Column 12,

lines 2-12, delete both of the structural formulae and alson the brackets and replace them by:

UNITED STATES PATENT OFFICE I CERTIFICATE OF CORRECTION Patent No. 3,859,341 Dated January 7, 1975 Inventor) Nils Ake Jonsson et al. Page 2 of 2 It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

W-O-fi-A-O O AC-OW Signed and Sealed this twenty-fourth D ay Of February 1976 [SEAL] Arrest:

RUTH C. MASON c. MARSHALL DANN Arresting Officer (ommissium'r uj'Parenrs and Trademarks 

1. A 3,33'' -DISUBSTITUTED BENZIDINE DERIVATIVE SELECTED FROM (A) THOSE HAVING THE GENERAL FORMULA
 2. The 3,3''-disubstituted benzidine derivative as claimed in claim 1, wherein W is hydrogen or an alkali metal cation.
 3. The 3,3''-disubstituted benzidine derivative as claimed in claim 1, wherein n is one.
 4. The 3,3''-disubstituted benzidine derivative as claimed in claim 3, wherein W is hydrogen.
 5. Gamma,gamma''-(4,4''-diamino-3,3''-biphenyldioxy)dibutyric acid.
 6. A hydrogen halogenic acid, sulfuric acid, phenylsulfonic acid, toluene sulfonic acid or naphthalene sulfonic acid addition salt as claimed in claim 1, wherein n is 1, A is a divalent trimethylene group, and W is hydrogen.
 7. The dihydrochloride of the 3,3''-disubstituted benzidine derivative as claimed in claim
 6. 8. The 3,3''-disubstituted derivative as claimed in claim 1, wherein n is zero.
 9. The 3,3''-disubstituted derivative as claimed in claim 8, wherein W is hydrogen.
 10. Delta,delta''-(4,4''-diamino-3,3''-biphenyl)divaleric acid. 